Results were coming in after U.K. food safety officials ordered supermarkets and suppliers to test all processed meals labeled as beef for traces of horsemeat.
Whitbread PLC, Britain's largest hotel and restaurant company, said horse DNA had been found in lasagna and burgers on its menus. The company, whose outlets include Premier Inn hotels and the Brewers Fayre and Beefeater Grill restaurant chains, said it was "shocked and disappointed at this failure of the processed meat supply chain."
Officials also said horsemeat was present in cottage pies delivered to 47 schools in Lancashire county, northern England, and in hospital meals in Northern Ireland. David Bingham, of the health service's Business Services Organization, said the hospital meals, from a supplier in the Republic of Ireland, had been withdrawn.
Several British supermarket chains, including Morrisons and Tesco, said Friday that tests on their products had so far been negative for horsemeat.
Duncan Campbell, a senior British food inspector, said the results would give a snapshot of the extent of the horsemeat contamination, which already has seen products pulled from supermarket shelves across Europe. But, he told the BBC, "I think there will be still more discoveries to be made."
"The more people have looked for horsemeat, the more products have been found containing it. I don't think we have got to the bottom of it yet," he said.
Officials from the European Union countries decided Friday to go ahead with a plan for more intensive checks to detect horsemeat in food labeled as beef.
In addition, horsemeat will be tested for phenylbutazone, or bute, an anti-inflammatory veterinary drug that's illegal to use in animals used for food.
EU Health Commissioner Tonio Borg welcomed the approval, saying, "consumers expect the EU, national authorities and all those involved in the food chain to give them all the reinsurance needed as regards what they have in their plates."
The testing will go on for a month, and may be extended for two months after that.
The testing will include 2,250 samples of foods labeled as containing beef, ranging from 10 to 150 per country. Tests for bute will be done on one sample for every 50 tons of meat.
The scandal, which erupted after Irish authorities found traces of horse DNA in frozen burgers last month, has grown to take in companies and countries across Europe.
NorgesGruppen, Norway's largest grocery retailer, said Friday that horsemeat has also been confirmed in frozen lasagna sold in its stores.
The escalating crisis has raised questions about food controls in the 27-nation European Union -- and highlighted how little consumers know about the complex trading operations that get food from producers to wholesalers to processers to stores and onto dinner tables.
Europol, the European Union police agency, is coordinating a continent-wide fraud investigation amid allegations of an international criminal conspiracy to substitute horse for more expensive beef.
French Consumer Affairs Minister Benoit Hamon said Thursday that it appeared fraudulent meat sales over several months reached across 13 countries and 28 companies. He identified French meat wholesaler Spanghero as a major culprit.
The company denied wrongdoing.
Spanghero chief Barthelemy Aguerre told RTL radio Friday that his company in southern France did receive a lot of horsemeat along with beef in its shipments "and we didn't touch" it. He did not provide details or specify whether he reported the horsemeat delivery, saying only, "I will prove my innocence."
Hamon said Spanghero was one company in a food production chain that started with two Romanian slaughterhouses, which say they clearly labeled their meat as horse.
The meat was then bought by a Cyprus-registered trader and sent to a warehouse in the Netherlands.
Spanghero bought the meat from the trader, then resold it to the French frozen food processor Comigel. The resulting food was marketed in Britain and other countries under the Sweden-based Findus brand as lasagna and other products containing ground beef.
Hamon said Spanghero was well aware that the meat was mislabeled when it sold it to Comigel.
But Aguerre, the Spanghero executive, said if there was a customs code indicating horsemeat, his company knew nothing about it.
The Dutch meat vendor involved, Draap, has also denied misleading anyone -- though the firm's lawyer acknowledged that Draap's director, Jan Fasen, had a previous conviction for mislabeling horsemeat as halal meat.
"Clients get what they order," lawyer Rogier Hoerchner said in a statement. "Draap cannot see what is on the label of end products."
No one has been charged yet over the current scandal, although British police on Thursday announced the arrests of three men on suspicion of fraud at two meat plants closed down by the country's Food Standards Agency.
Hinnant reported from Paris. Mike Corder in Amsterdam, Karl Ritter in Stockholm and Don Melvin in Brussels contributed to this report.
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